Protective system for diesel engines



{mite Seates Patent 1m entor Warren .1. Lockmuller Oakland, New Jersey Appl. No. 808.418 Filed March 19, 1969 Patented Oct. 13, 1970 Assignee The Nycal Company. Inc.

(larlstadl, New Jersey a corporation of New Jerse PROTECTIVE SYSTEM FOR DIESEL ENGTNES 7 Claims, 1 Drawing Fig.

[52] L'.S.C1 123/198. 123/41.15.1Z3/179 [51] Int. (ll F02b 77/08 {5(1) Fieldoi'Search ..l23/198(D3), 198(D2). 198(Dl), 198.41.15, 179/13) 179 [5 6] References Cited L'NlTED STATES PATENTS 2,112,664 3/1938 Dube 123/4114 2.162.174 6/1939 Jones 2.370.249 2/1945 Korte 123/179 2.373.735 4/1945 Alexander 123/179 2.565.984 8/1951 Newman et a1. l23/198X 2.603.690 7/1952 Moody 123/198X 2.930.365 3/1960 Muscato 123144.15 3,116.729 1/1964 Crowe e. 123179 3.362.388 1/1968 Lindberg et 211.. 123/198X 3.3841162 5/1968 Boyer 123/198 FOREIGN PATENTS 1.047.923 7/1953 France 123/198 Primary Examiner-Wendell E. Burns Attorney-Albert F. Kronman ABSTRACT: A protective system for diesel'engines using injection pumps and rack. The engine is stopped automatically by opening the supply circuit to the rack solenoid whenever the engine is overheated or the oil pressure is too low. Circuitry is provided which permits an operator to start the engine when there is little or no oil pressure.

Patented Oct; 13, 1970 INVENTOR. I A/4 B BZA/ Jar/Ka la ATTORNEY 1 PROTECTIVE SYSTEM roe nursur. enemas BACKGROUND OF THE INVENTION This invention relates to a protective system for diesel engines and operates to turn off the rack solenoid and stop the engine whenever the engine is heated above a maximum temperature or when the oil pressure falls below a minimum value.

Modern diesel engines are reasonably well adjusted for temperature variations and for a constant oil pressure. Various compensating devices have been used to maintain the temperature of the engine and the pressure of the oil within desired ranges at all speeds and all ambient conditions. However, when the oil is partially consumed or when the oil pump fails, the compensating devices cannot keep the oil pressure at a safe value and severe damage may result. In like manner, there are times when the engine coolant system is blocked and the temperature of the engine rises above a safe value. Continued operation of the engine under these conditions causes serious damage. The present invention stops the engine when ever these conditions are present before there is damage to the engine due to careless operation.

DESCRIPTION OF THE DRAWING The single figure is a schematic diagram of connections showing the invention applied to a diesel engine.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the FIG., the protective system includes a temperature sensing means which is secured to some portion of the cooling system such as a conduit 11 carrying a liquid coolant 12. Best results are obtained when the sensing means includes a screw 13 made of heat conductive material, such as copper or brass. threaded into a wall of the conduit 11 so that the end of the screw is in direct contact with the liquid coolant l2. Screw 13 is terminated by a flat disk portion 14 on which a bimetallic strip 15 is positioned. The strip is secured at one end by a screw 16 while a contact disk 17 is welded to the other end. A cooperating contact disk 18 is mounted on a short strip 20 above the contact disk 17. An insulator block 21 holds strip 20 in place. A dust cover 22 may be mounted over the contacts to keep them clean. The, bimetallic strip is mounted so that it will bend upwardly and force contacts 17 and 18 to close when the temperature of the liquid coolant 12 rises above the normal or safe temperature, generally 220 F. The bimetallic strip 15 is connected to a conductor 23, which may be grounded, while the short strip 20 is connected to conductor 24.

A pressure sensing device 25 is mounted on one of the conduits 26 which convey lubricating oil 27 from an oil pump (not shown) to the engine parts to be lubricated. A short conduit 28 is threaded into the oil conduit 26 and its upperend is terminated by a flat flange 30 across which an elastic metal diaphragm 31 is mounted. The diaphragm is secured only at its outer edge so that it can be flexed or bowed upwardly by the pressure in conduit 26. An insulator knob 32 is mounted at the center of diaphragm 31 and is designed to make contact with a flexible conductive strip 33, secured to a support at one end and carrying a contact disk 35 at its other end. When the oil is not under pressure, diaphragm 30 is flat and contact disk 35 rests on another contact disk 36, secured to a short conductive strip 37 mounted in an insulator block 38. Contacts 34 and 35 remain closed until the pressure of the oil in conduit 26 forces the diaphragmup and separates the contacts as shown in the figure. In the normal running position, contacts 35 and 36 remain open.

Contacts 17 and 18 in the temperature sensing means 10 and contacts 34 and 35 in the pressure sensing means are connected in parallel with each other and the two contact pairs are in series with a winding 40 of a guard relay 41 having a normally closed pair of contacts 42. The guard relay is operated only when the coolant temperature is too high or when oil pressure is too low. The other end of winding 40 is connected to a conductor 43 and in series with an injection switch 44. The other side of switch 44 is connected to the positive terminal of a storage battery 45.

Diesel motors receive their fuel from an injection pump 46 which pumps the fuel through a slide valve 47 to a conduit 48 and the cylinders of the motor. The opening and closing of valve 47 is controlled by a rack 50 and a rack solenoid 51. The solenoid 51 has one terminal connected to the negative terminal of battery 45 and the other terminal connected to the positive terminal in series with contacts 42 of the guard relay and the injection switch 44. v

A start motor 53 is mechanically connected to the crank shaft of the engine in an engine block 54. A clutch 55 may be connected between start motor 48 and the engine if desired. The start motor 53 is powered by the battery 45 and controlled by a start relay 56 having apair of normally open contacts 57. When contacts 57 are closed, the full power of the battery is applied to the motor 53 to turn the crank shaft. The start relay 56 includes a winding 58 connected to the battery 45 in series with a manually operated start switch 60.

The circuit shown in the figure includes no indicated ground connection. However, common conductor 23 is connected to the conduit 11 and also to the oil conduit 26.1t is obvious that suitable insulating coupling means can be inserted at these sensing means to isolate the circuit from the piping. Also, it is obvious that the polarity of the battery 45 may be changed, if desired, without changing the operation of the system.

The operation of this protective system is as follows: the engine is started by first closing the injection switch 44 and then depressing the start switch 60. This action operates relay 58, closing contacts 57 and operating the start motor 53. When the injection switch 44 is closed, the guard relay 41 is operated since current flows through the relay winding 40, closed contacts 35, 36, to the negative terminal of the battery over conductor 23. Contacts 42 are opened and remain open until the oil pressure is great enough to move diaphragm 31 and open contacts 35, 36. On some engines the oil pressure may be increased quickly and the engine started after only a few revolutions. On other engines it is necessary for the operator to depress both the start switch 60 and an over rule switch 61 in order to operate the injection solenoid 47 when the oil pressure is low.

With the engine running normally, contacts 17 and 1% remain open because the engine coolant is below a maximum temperature. Also, the oil pressure maintains contacts 35 and 36 open and the guard relay contacts 42 are closed. If the oil pressure drops below a predetermined value, contacts 35, 36 are closed, the guard relay 41 is operated and contacts 42 are opened, stopping the engine because the rack solenoid 51 is not operated to open valve 47. In a similar manner, if the engine gets too hot. the temperature of the, coolant closes contacts 17, 18 and contacts 42 are again opened.

If the protective system operates to stop the engine at a time i when the vehicle is in the middle of traffic, the operator may again depress the over rule switch 61 and continue to run the engine until the vehicle is moved to a position out of traffic where repairs can be made. The pressure sensing means 251s generally set to close contacts 35, 36 whenever the pressure falls below 12 pounds per square inch.

lclaim:

l. A protective system for diesel engines employing pistons in combustion chambers comprising:

a. a temperature sensing means coupled to a portion of the engine and including a pair of normally open electrical contacts which close when the temperature of the engine rises above a predetermined value;

b. a pressure sensing means coupled to the lubricating oil system of the engine and including a resilient diaphragm responsive to the pressure in the oil system and a pair of contacts coupled to the diaphragm which remain open as long as the oil pressure is above a predetermined value and the diaphragm is stressed;

c. a rack solenoid controlling a fuel valve in series with the engine combustion chambers and an injection pump for injecting liquid fuel into the chambers;

d. an electrical start motor mechanically coupled to the engine for starting it; e

e. a start relay including a winding connected in series with a source of electrical power and a start switch, and a pair of contacts connected in series with the start motor and the source of electrical power; and

f. a guard relay for disabling the fuel injection means including a pair of normally closed contacts connected in series with the source of electrical power and a rack solenoid which operates a valve between the combustion cham bers and the injection pump, and a winding connected in series with the electrical source of power and the contacts in the temperature sensing means and the pressure sensing means.

2. A protective system as claimed in claim 1 wherein the pair of contacts in the temperature sensing means is coupled to a bimetallic strip which is distorted when the temperature changes.

3. A protective system as claimed in claim 1 wherein said pressure sensing means is connected to an oil conduit connected to the high pressure side of an oil pump.

4. A protective system as claimed in claim 1 wherein the rack solenoid is mechanically connected to a slide valve which controls the amount of fuel supplied to the combustion cylinders.

5. A protective system as claimed in claim 1 wherein an over rule switch is connected in parallel with the contacts of the guard relay for starting and for emergency operation of the engine.

6. A protective system as claimed in claim 1 wherein said diaphragm has one surface positioned for direct contact with the oil in the oil system.

7. A protective system as claimed in claim 1 wherein said temperature sensitive means includes a threaded copper screw positioned in a wall of a conduit containing engine coolant. 

